fuel pressure/duty

[killmode_on]

The factory E38 ECU monitors and compensates for dropping pressure delta with increased duty if you have enough injector available. I've tested from 43psi to 58psi changing nothing but fuel pressure. No difference in AFR's or power output. Using pressure the way you want, to make your huge injectors idle well or to make your fuel pump deliver some more volume or to get your too small of injectors to keep up with demand, it's all up to your tuner.

[Nitroman28]

Originally Posted by Crime2

What injectors are you using?


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Got FIC 60lb.

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[Nitroman28]

It's commanding 67psi.

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[Nitroman28]

Originally Posted by killmode_on

The factory E38 ECU monitors and compensates for dropping pressure delta with increased duty if you have enough injector available. I've tested from 43psi to 58psi changing nothing but fuel pressure. No difference in AFR's or power output. Using pressure the way you want, to make your huge injectors idle well or to make your fuel pump deliver some more volume or to get your too small of injectors to keep up with demand, it's all up to your tuner.

I've tried setting the duty cycle to 100% like Livernois suggested but no change. I even put a KB on and noticed no change.

[killmode_on]

Originally Posted by Nitroman28

I've tried setting the duty cycle to 100% like Livernois suggested but no change. I even put a KB on and noticed no change.

Maybe you have in in tank leak. Dual pumps should be way more than enough.

[stevieturbo]

Originally Posted by killmode_on

The factory E38 ECU monitors and compensates for dropping pressure delta with increased duty if you have enough injector available. I've tested from 43psi to 58psi changing nothing but fuel pressure. No difference in AFR's or power output. Using pressure the way you want, to make your huge injectors idle well or to make your fuel pump deliver some more volume or to get your too small of injectors to keep up with demand, it's all up to your tuner.

That's ok up to a point, but blindly allowing closed loop changes without monitoring for safety carries it's own risks

If you did have a fuel supply issue, just like the in-tank leak you mention, you'd happily carry on thinking because AFR's seem ok, all is well. Then all of a sudden engine goes bang because fuel pressure kept dropping as you had no idea there was a problem. Trying to use closed loop to band aid a problem is not the correct way to do things

If you monitor FP, then you'd see straight away there is a problem. Even better if the ecu can monitor it real time and relative to intake manifold pressure, and alert you or cause a limp mode if there is a problem to report.

[sting808]

Originally Posted by Nitroman28

Got FIC 60lb.

Sent from my HTC One using Tapatalk 2

I have a LS3 w/KB 2.8. With the KB BAP, boost at 10.5, FP would drop to 45-46 PSI. This is using the kit Deka 60lbs injectors running at 78%. AFR was good throughout the dyno runs, but didn't like FP dropping to 45PSI. Also, idle and low speed driveability could've been better. This was with a custom tune.

Recently, I added the ZL1 pump/ADM FPCM, ID1000 and now the car runs great. Boost dropped a little to upper 9s, but FP stays solid +58 to 4500rpm, then bumps to +65 and doesn't dip. Commanded is 66.7. Kept the KB BAP. ID1000s are running at max 41%. I know the L99s require more pressure, but would think the ZL1/ADM would keep up, let alone the dual pump setup.

I thought the ID1000s would be too big, but what do I know... The IDs helped my idle and low speed driveability where FP was not an issue. AFRs were always good before and after. Something doesn't sound right if FP is dropping to 47. Wonder if larger injectors will help you with better efficiency.

[JANNETTYRACING]

Originally Posted by Nitroman28

My motor just don't seem to be very efficient. After the maggie I put the ZL1/ADM controller in and pressure was dropping to 39-40psi. AFR was holding good but would lean out past 6000. So I bought the Livernois dual pump. FP still drops 47psi at 6000+.IDC is around 75%. I put a KB on it but it seem to have no affect on it. I finally just said the hell with it. AFR holds good thru the run.

The injectors Play a big roll in Fuel pressure at high duty cycles.

With the ZR1 injectors that come standard in the maggie anything above 550 RWHP a single pump has a hard time keeping up because the injectors are Maxed out.

Also Keep in Mind Richer AFR causes Lower Fuel Pressure simply due to fuel consumption is higher.

We have seen this with the ZL1 Pump and ADM controller Just add ID-850s and the fuel pressure no longer drops.

This is because of recover time is increased between injector events.

With small injectors they Nearly can all be open at the same time.

With large injectors the injector events are shorter increasing the close time allowing the fuel pump to keep up.

Ted.

[pdiddy]

good info thanks, I am probably going to the zl1 pump and adm fpcm and run the 3.6 pulley over the winter but I have a feeling I will need better injectors also as I am making 540 now so I will be just under 600 and it sounds like the zr1 injectors will not be good enough to keep up then

[JANNETTYRACING]

Originally Posted by pdiddy

good info thanks, I am probably going to the zl1 pump and adm fpcm and run the 3.6 pulley over the winter but I have a feeling I will need better injectors also as I am making 540 now so I will be just under 600 and it sounds like the zr1 injectors will not be good enough to keep up then

Your Welcome!

It is very Unlikely your making 540 RWHP with a 3.8 pulley, Unless of coarse your running an Overdrive Cog or a 3.6.

But I agree that the ID-850s are your best investment.

Ted.

[Nitroman28]

Originally Posted by JANNETTYRACING

The injectors Play a big roll in Fuel pressure at high duty cycles.

With the ZR1 injectors that come standard in the maggie anything above 550 RWHP a single pump has a hard time keeping up because the injectors are Maxed out.

Also Keep in Mind Richer AFR causes Lower Fuel Pressure simply due to fuel consumption is higher.

We have seen this with the ZL1 Pump and ADM controller Just add ID-850s and the fuel pressure no longer drops.

This is because of recover time is increased between injector events.

With small injectors they Nearly can all be open at the same time.

With large injectors the injector events are shorter increasing the close time allowing the fuel pump to keep up.

Ted.

If I was to switch to the ID850's would a lot of tuning need to be done to make them work or just the Data for the injector entered?

[pdiddy]

Ted I can only speek for the numbers that where shown on the dyno I would imagine I am making pretty close to what they say as the car was dynoed at 406 before the blower and according to my boost gauge I am making 6lbs I have a CAI so this I believe is about right for boost. If 20hp per lb of boost is close to accurate I think the numbers are close I am going to attach my dyno graph so I am not just that guy that says things

[pdiddy]

just a little more info the 406 number was on a differnt dyno in OK the 540 that u see in the attached is here in MO from my local tuner Just Tune

[Iam Broke]

Originally Posted by Nitroman28

If I was to switch to the ID850's would a lot of tuning need to be done to make them work or just the Data for the injector entered?

The data for the ID850's is pretty accurate but your FIC's prob not so much. I believe some dialing in will be needed. I went from FIC 60's to the ID850's last spring and it took several % here & there to bring it in.